xref: /titanic_52/usr/src/uts/common/fs/zfs/dmu.c (revision 700c902c445eb3882848aaddc19d13638818cfd6)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 
26 #pragma ident	"%Z%%M%	%I%	%E% SMI"
27 
28 #include <sys/dmu.h>
29 #include <sys/dmu_impl.h>
30 #include <sys/dmu_tx.h>
31 #include <sys/dbuf.h>
32 #include <sys/dnode.h>
33 #include <sys/zfs_context.h>
34 #include <sys/dmu_objset.h>
35 #include <sys/dmu_traverse.h>
36 #include <sys/dsl_dataset.h>
37 #include <sys/dsl_dir.h>
38 #include <sys/dsl_pool.h>
39 #include <sys/dsl_synctask.h>
40 #include <sys/dmu_zfetch.h>
41 #include <sys/zfs_ioctl.h>
42 #include <sys/zap.h>
43 #include <sys/zio_checksum.h>
44 
45 const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES] = {
46 	{	byteswap_uint8_array,	TRUE,	"unallocated"		},
47 	{	zap_byteswap,		TRUE,	"object directory"	},
48 	{	byteswap_uint64_array,	TRUE,	"object array"		},
49 	{	byteswap_uint8_array,	TRUE,	"packed nvlist"		},
50 	{	byteswap_uint64_array,	TRUE,	"packed nvlist size"	},
51 	{	byteswap_uint64_array,	TRUE,	"bplist"		},
52 	{	byteswap_uint64_array,	TRUE,	"bplist header"		},
53 	{	byteswap_uint64_array,	TRUE,	"SPA space map header"	},
54 	{	byteswap_uint64_array,	TRUE,	"SPA space map"		},
55 	{	byteswap_uint64_array,	TRUE,	"ZIL intent log"	},
56 	{	dnode_buf_byteswap,	TRUE,	"DMU dnode"		},
57 	{	dmu_objset_byteswap,	TRUE,	"DMU objset"		},
58 	{	byteswap_uint64_array,	TRUE,	"DSL directory"		},
59 	{	zap_byteswap,		TRUE,	"DSL directory child map"},
60 	{	zap_byteswap,		TRUE,	"DSL dataset snap map"	},
61 	{	zap_byteswap,		TRUE,	"DSL props"		},
62 	{	byteswap_uint64_array,	TRUE,	"DSL dataset"		},
63 	{	zfs_znode_byteswap,	TRUE,	"ZFS znode"		},
64 	{	zfs_acl_byteswap,	TRUE,	"ZFS ACL"		},
65 	{	byteswap_uint8_array,	FALSE,	"ZFS plain file"	},
66 	{	zap_byteswap,		TRUE,	"ZFS directory"		},
67 	{	zap_byteswap,		TRUE,	"ZFS master node"	},
68 	{	zap_byteswap,		TRUE,	"ZFS delete queue"	},
69 	{	byteswap_uint8_array,	FALSE,	"zvol object"		},
70 	{	zap_byteswap,		TRUE,	"zvol prop"		},
71 	{	byteswap_uint8_array,	FALSE,	"other uint8[]"		},
72 	{	byteswap_uint64_array,	FALSE,	"other uint64[]"	},
73 	{	zap_byteswap,		TRUE,	"other ZAP"		},
74 	{	zap_byteswap,		TRUE,	"persistent error log"	},
75 };
76 
77 int
78 dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset,
79     void *tag, dmu_buf_t **dbp)
80 {
81 	dnode_t *dn;
82 	uint64_t blkid;
83 	dmu_buf_impl_t *db;
84 	int err;
85 
86 	err = dnode_hold(os->os, object, FTAG, &dn);
87 	if (err)
88 		return (err);
89 	blkid = dbuf_whichblock(dn, offset);
90 	rw_enter(&dn->dn_struct_rwlock, RW_READER);
91 	db = dbuf_hold(dn, blkid, tag);
92 	rw_exit(&dn->dn_struct_rwlock);
93 	if (db == NULL) {
94 		err = EIO;
95 	} else {
96 		err = dbuf_read(db, NULL, DB_RF_CANFAIL);
97 		if (err) {
98 			dbuf_rele(db, tag);
99 			db = NULL;
100 		}
101 	}
102 
103 	dnode_rele(dn, FTAG);
104 	*dbp = &db->db;
105 	return (err);
106 }
107 
108 int
109 dmu_bonus_max(void)
110 {
111 	return (DN_MAX_BONUSLEN);
112 }
113 
114 /*
115  * returns ENOENT, EIO, or 0.
116  */
117 int
118 dmu_bonus_hold(objset_t *os, uint64_t object, void *tag, dmu_buf_t **dbp)
119 {
120 	dnode_t *dn;
121 	int err, count;
122 	dmu_buf_impl_t *db;
123 
124 	err = dnode_hold(os->os, object, FTAG, &dn);
125 	if (err)
126 		return (err);
127 
128 	rw_enter(&dn->dn_struct_rwlock, RW_READER);
129 	if (dn->dn_bonus == NULL) {
130 		rw_exit(&dn->dn_struct_rwlock);
131 		rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
132 		if (dn->dn_bonus == NULL)
133 			dn->dn_bonus = dbuf_create_bonus(dn);
134 	}
135 	db = dn->dn_bonus;
136 	rw_exit(&dn->dn_struct_rwlock);
137 	mutex_enter(&db->db_mtx);
138 	count = refcount_add(&db->db_holds, tag);
139 	mutex_exit(&db->db_mtx);
140 	if (count == 1)
141 		dnode_add_ref(dn, db);
142 	dnode_rele(dn, FTAG);
143 
144 	VERIFY(0 == dbuf_read(db, NULL, DB_RF_MUST_SUCCEED));
145 
146 	*dbp = &db->db;
147 	return (0);
148 }
149 
150 /*
151  * Note: longer-term, we should modify all of the dmu_buf_*() interfaces
152  * to take a held dnode rather than <os, object> -- the lookup is wasteful,
153  * and can induce severe lock contention when writing to several files
154  * whose dnodes are in the same block.
155  */
156 static int
157 dmu_buf_hold_array_by_dnode(dnode_t *dn, uint64_t offset,
158     uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp)
159 {
160 	dmu_buf_t **dbp;
161 	uint64_t blkid, nblks, i;
162 	uint32_t flags;
163 	int err;
164 	zio_t *zio;
165 
166 	ASSERT(length <= DMU_MAX_ACCESS);
167 
168 	flags = DB_RF_CANFAIL | DB_RF_NEVERWAIT;
169 	if (length > zfetch_array_rd_sz)
170 		flags |= DB_RF_NOPREFETCH;
171 
172 	rw_enter(&dn->dn_struct_rwlock, RW_READER);
173 	if (dn->dn_datablkshift) {
174 		int blkshift = dn->dn_datablkshift;
175 		nblks = (P2ROUNDUP(offset+length, 1ULL<<blkshift) -
176 			P2ALIGN(offset, 1ULL<<blkshift)) >> blkshift;
177 	} else {
178 		ASSERT3U(offset + length, <=, dn->dn_datablksz);
179 		nblks = 1;
180 	}
181 	dbp = kmem_zalloc(sizeof (dmu_buf_t *) * nblks, KM_SLEEP);
182 
183 	zio = zio_root(dn->dn_objset->os_spa, NULL, NULL, TRUE);
184 	blkid = dbuf_whichblock(dn, offset);
185 	for (i = 0; i < nblks; i++) {
186 		dmu_buf_impl_t *db = dbuf_hold(dn, blkid+i, tag);
187 		if (db == NULL) {
188 			rw_exit(&dn->dn_struct_rwlock);
189 			dmu_buf_rele_array(dbp, nblks, tag);
190 			zio_nowait(zio);
191 			return (EIO);
192 		}
193 		/* initiate async i/o */
194 		if (read) {
195 			rw_exit(&dn->dn_struct_rwlock);
196 			(void) dbuf_read(db, zio, flags);
197 			rw_enter(&dn->dn_struct_rwlock, RW_READER);
198 		}
199 		dbp[i] = &db->db;
200 	}
201 	rw_exit(&dn->dn_struct_rwlock);
202 
203 	/* wait for async i/o */
204 	err = zio_wait(zio);
205 	if (err) {
206 		dmu_buf_rele_array(dbp, nblks, tag);
207 		return (err);
208 	}
209 
210 	/* wait for other io to complete */
211 	if (read) {
212 		for (i = 0; i < nblks; i++) {
213 			dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbp[i];
214 			mutex_enter(&db->db_mtx);
215 			while (db->db_state == DB_READ ||
216 			    db->db_state == DB_FILL)
217 				cv_wait(&db->db_changed, &db->db_mtx);
218 			if (db->db_state == DB_UNCACHED)
219 				err = EIO;
220 			mutex_exit(&db->db_mtx);
221 			if (err) {
222 				dmu_buf_rele_array(dbp, nblks, tag);
223 				return (err);
224 			}
225 		}
226 	}
227 
228 	*numbufsp = nblks;
229 	*dbpp = dbp;
230 	return (0);
231 }
232 
233 int
234 dmu_buf_hold_array(objset_t *os, uint64_t object, uint64_t offset,
235     uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp)
236 {
237 	dnode_t *dn;
238 	int err;
239 
240 	err = dnode_hold(os->os, object, FTAG, &dn);
241 	if (err)
242 		return (err);
243 
244 	err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
245 	    numbufsp, dbpp);
246 
247 	dnode_rele(dn, FTAG);
248 
249 	return (err);
250 }
251 
252 int
253 dmu_buf_hold_array_by_bonus(dmu_buf_t *db, uint64_t offset,
254     uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp)
255 {
256 	dnode_t *dn = ((dmu_buf_impl_t *)db)->db_dnode;
257 	int err;
258 
259 	err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
260 	    numbufsp, dbpp);
261 
262 	return (err);
263 }
264 
265 void
266 dmu_buf_rele_array(dmu_buf_t **dbp_fake, int numbufs, void *tag)
267 {
268 	int i;
269 	dmu_buf_impl_t **dbp = (dmu_buf_impl_t **)dbp_fake;
270 
271 	if (numbufs == 0)
272 		return;
273 
274 	for (i = 0; i < numbufs; i++) {
275 		if (dbp[i])
276 			dbuf_rele(dbp[i], tag);
277 	}
278 
279 	kmem_free(dbp, sizeof (dmu_buf_t *) * numbufs);
280 }
281 
282 void
283 dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset, uint64_t len)
284 {
285 	dnode_t *dn;
286 	uint64_t blkid;
287 	int nblks, i, err;
288 
289 	if (len == 0) {  /* they're interested in the bonus buffer */
290 		dn = os->os->os_meta_dnode;
291 
292 		if (object == 0 || object >= DN_MAX_OBJECT)
293 			return;
294 
295 		rw_enter(&dn->dn_struct_rwlock, RW_READER);
296 		blkid = dbuf_whichblock(dn, object * sizeof (dnode_phys_t));
297 		dbuf_prefetch(dn, blkid);
298 		rw_exit(&dn->dn_struct_rwlock);
299 		return;
300 	}
301 
302 	/*
303 	 * XXX - Note, if the dnode for the requested object is not
304 	 * already cached, we will do a *synchronous* read in the
305 	 * dnode_hold() call.  The same is true for any indirects.
306 	 */
307 	err = dnode_hold(os->os, object, FTAG, &dn);
308 	if (err != 0)
309 		return;
310 
311 	rw_enter(&dn->dn_struct_rwlock, RW_READER);
312 	if (dn->dn_datablkshift) {
313 		int blkshift = dn->dn_datablkshift;
314 		nblks = (P2ROUNDUP(offset+len, 1<<blkshift) -
315 			P2ALIGN(offset, 1<<blkshift)) >> blkshift;
316 	} else {
317 		nblks = (offset < dn->dn_datablksz);
318 	}
319 
320 	if (nblks != 0) {
321 		blkid = dbuf_whichblock(dn, offset);
322 		for (i = 0; i < nblks; i++)
323 			dbuf_prefetch(dn, blkid+i);
324 	}
325 
326 	rw_exit(&dn->dn_struct_rwlock);
327 
328 	dnode_rele(dn, FTAG);
329 }
330 
331 int
332 dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
333     uint64_t size, dmu_tx_t *tx)
334 {
335 	dnode_t *dn;
336 	int err = dnode_hold(os->os, object, FTAG, &dn);
337 	if (err)
338 		return (err);
339 	ASSERT(offset < UINT64_MAX);
340 	ASSERT(size == -1ULL || size <= UINT64_MAX - offset);
341 	dnode_free_range(dn, offset, size, tx);
342 	dnode_rele(dn, FTAG);
343 	return (0);
344 }
345 
346 int
347 dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
348     void *buf)
349 {
350 	dnode_t *dn;
351 	dmu_buf_t **dbp;
352 	int numbufs, i, err;
353 
354 	/*
355 	 * Deal with odd block sizes, where there can't be data past the
356 	 * first block.
357 	 */
358 	err = dnode_hold(os->os, object, FTAG, &dn);
359 	if (err)
360 		return (err);
361 	if (dn->dn_datablkshift == 0) {
362 		int newsz = offset > dn->dn_datablksz ? 0 :
363 		    MIN(size, dn->dn_datablksz - offset);
364 		bzero((char *)buf + newsz, size - newsz);
365 		size = newsz;
366 	}
367 	dnode_rele(dn, FTAG);
368 
369 	while (size > 0) {
370 		uint64_t mylen = MIN(size, DMU_MAX_ACCESS / 2);
371 		int err;
372 
373 		/*
374 		 * NB: we could do this block-at-a-time, but it's nice
375 		 * to be reading in parallel.
376 		 */
377 		err = dmu_buf_hold_array(os, object, offset, mylen,
378 		    TRUE, FTAG, &numbufs, &dbp);
379 		if (err)
380 			return (err);
381 
382 		for (i = 0; i < numbufs; i++) {
383 			int tocpy;
384 			int bufoff;
385 			dmu_buf_t *db = dbp[i];
386 
387 			ASSERT(size > 0);
388 
389 			bufoff = offset - db->db_offset;
390 			tocpy = (int)MIN(db->db_size - bufoff, size);
391 
392 			bcopy((char *)db->db_data + bufoff, buf, tocpy);
393 
394 			offset += tocpy;
395 			size -= tocpy;
396 			buf = (char *)buf + tocpy;
397 		}
398 		dmu_buf_rele_array(dbp, numbufs, FTAG);
399 	}
400 	return (0);
401 }
402 
403 void
404 dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
405     const void *buf, dmu_tx_t *tx)
406 {
407 	dmu_buf_t **dbp;
408 	int numbufs, i;
409 
410 	if (size == 0)
411 		return;
412 
413 	VERIFY(0 == dmu_buf_hold_array(os, object, offset, size,
414 	    FALSE, FTAG, &numbufs, &dbp));
415 
416 	for (i = 0; i < numbufs; i++) {
417 		int tocpy;
418 		int bufoff;
419 		dmu_buf_t *db = dbp[i];
420 
421 		ASSERT(size > 0);
422 
423 		bufoff = offset - db->db_offset;
424 		tocpy = (int)MIN(db->db_size - bufoff, size);
425 
426 		ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
427 
428 		if (tocpy == db->db_size)
429 			dmu_buf_will_fill(db, tx);
430 		else
431 			dmu_buf_will_dirty(db, tx);
432 
433 		bcopy(buf, (char *)db->db_data + bufoff, tocpy);
434 
435 		if (tocpy == db->db_size)
436 			dmu_buf_fill_done(db, tx);
437 
438 		offset += tocpy;
439 		size -= tocpy;
440 		buf = (char *)buf + tocpy;
441 	}
442 	dmu_buf_rele_array(dbp, numbufs, FTAG);
443 }
444 
445 #ifdef _KERNEL
446 int
447 dmu_write_uio(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
448     uio_t *uio, dmu_tx_t *tx)
449 {
450 	dmu_buf_t **dbp;
451 	int numbufs, i;
452 	int err = 0;
453 
454 	if (size == 0)
455 		return (0);
456 
457 	err = dmu_buf_hold_array(os, object, offset, size,
458 	    FALSE, FTAG, &numbufs, &dbp);
459 	if (err)
460 		return (err);
461 
462 	for (i = 0; i < numbufs; i++) {
463 		int tocpy;
464 		int bufoff;
465 		dmu_buf_t *db = dbp[i];
466 
467 		ASSERT(size > 0);
468 
469 		bufoff = offset - db->db_offset;
470 		tocpy = (int)MIN(db->db_size - bufoff, size);
471 
472 		ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
473 
474 		if (tocpy == db->db_size)
475 			dmu_buf_will_fill(db, tx);
476 		else
477 			dmu_buf_will_dirty(db, tx);
478 
479 		/*
480 		 * XXX uiomove could block forever (eg. nfs-backed
481 		 * pages).  There needs to be a uiolockdown() function
482 		 * to lock the pages in memory, so that uiomove won't
483 		 * block.
484 		 */
485 		err = uiomove((char *)db->db_data + bufoff, tocpy,
486 		    UIO_WRITE, uio);
487 
488 		if (tocpy == db->db_size)
489 			dmu_buf_fill_done(db, tx);
490 
491 		if (err)
492 			break;
493 
494 		offset += tocpy;
495 		size -= tocpy;
496 	}
497 	dmu_buf_rele_array(dbp, numbufs, FTAG);
498 	return (err);
499 }
500 #endif
501 
502 /*
503  * XXX move send/recv stuff to its own new file!
504  */
505 
506 struct backuparg {
507 	dmu_replay_record_t *drr;
508 	vnode_t *vp;
509 	objset_t *os;
510 	zio_cksum_t zc;
511 	int err;
512 };
513 
514 static int
515 dump_bytes(struct backuparg *ba, void *buf, int len)
516 {
517 	ssize_t resid; /* have to get resid to get detailed errno */
518 	ASSERT3U(len % 8, ==, 0);
519 
520 	fletcher_4_incremental_native(buf, len, &ba->zc);
521 	ba->err = vn_rdwr(UIO_WRITE, ba->vp,
522 	    (caddr_t)buf, len,
523 	    0, UIO_SYSSPACE, FAPPEND, RLIM64_INFINITY, CRED(), &resid);
524 	return (ba->err);
525 }
526 
527 static int
528 dump_free(struct backuparg *ba, uint64_t object, uint64_t offset,
529     uint64_t length)
530 {
531 	/* write a FREE record */
532 	bzero(ba->drr, sizeof (dmu_replay_record_t));
533 	ba->drr->drr_type = DRR_FREE;
534 	ba->drr->drr_u.drr_free.drr_object = object;
535 	ba->drr->drr_u.drr_free.drr_offset = offset;
536 	ba->drr->drr_u.drr_free.drr_length = length;
537 
538 	if (dump_bytes(ba, ba->drr, sizeof (dmu_replay_record_t)))
539 		return (EINTR);
540 	return (0);
541 }
542 
543 static int
544 dump_data(struct backuparg *ba, dmu_object_type_t type,
545     uint64_t object, uint64_t offset, int blksz, void *data)
546 {
547 	/* write a DATA record */
548 	bzero(ba->drr, sizeof (dmu_replay_record_t));
549 	ba->drr->drr_type = DRR_WRITE;
550 	ba->drr->drr_u.drr_write.drr_object = object;
551 	ba->drr->drr_u.drr_write.drr_type = type;
552 	ba->drr->drr_u.drr_write.drr_offset = offset;
553 	ba->drr->drr_u.drr_write.drr_length = blksz;
554 
555 	if (dump_bytes(ba, ba->drr, sizeof (dmu_replay_record_t)))
556 		return (EINTR);
557 	if (dump_bytes(ba, data, blksz))
558 		return (EINTR);
559 	return (0);
560 }
561 
562 static int
563 dump_freeobjects(struct backuparg *ba, uint64_t firstobj, uint64_t numobjs)
564 {
565 	/* write a FREEOBJECTS record */
566 	bzero(ba->drr, sizeof (dmu_replay_record_t));
567 	ba->drr->drr_type = DRR_FREEOBJECTS;
568 	ba->drr->drr_u.drr_freeobjects.drr_firstobj = firstobj;
569 	ba->drr->drr_u.drr_freeobjects.drr_numobjs = numobjs;
570 
571 	if (dump_bytes(ba, ba->drr, sizeof (dmu_replay_record_t)))
572 		return (EINTR);
573 	return (0);
574 }
575 
576 static int
577 dump_dnode(struct backuparg *ba, uint64_t object, dnode_phys_t *dnp)
578 {
579 	if (dnp == NULL || dnp->dn_type == DMU_OT_NONE)
580 		return (dump_freeobjects(ba, object, 1));
581 
582 	/* write an OBJECT record */
583 	bzero(ba->drr, sizeof (dmu_replay_record_t));
584 	ba->drr->drr_type = DRR_OBJECT;
585 	ba->drr->drr_u.drr_object.drr_object = object;
586 	ba->drr->drr_u.drr_object.drr_type = dnp->dn_type;
587 	ba->drr->drr_u.drr_object.drr_bonustype = dnp->dn_bonustype;
588 	ba->drr->drr_u.drr_object.drr_blksz =
589 	    dnp->dn_datablkszsec << SPA_MINBLOCKSHIFT;
590 	ba->drr->drr_u.drr_object.drr_bonuslen = dnp->dn_bonuslen;
591 	ba->drr->drr_u.drr_object.drr_checksum = dnp->dn_checksum;
592 	ba->drr->drr_u.drr_object.drr_compress = dnp->dn_compress;
593 
594 	if (dump_bytes(ba, ba->drr, sizeof (dmu_replay_record_t)))
595 		return (EINTR);
596 
597 	if (dump_bytes(ba, DN_BONUS(dnp), P2ROUNDUP(dnp->dn_bonuslen, 8)))
598 		return (EINTR);
599 
600 	/* free anything past the end of the file */
601 	if (dump_free(ba, object, (dnp->dn_maxblkid + 1) *
602 	    (dnp->dn_datablkszsec << SPA_MINBLOCKSHIFT), -1ULL))
603 		return (EINTR);
604 	if (ba->err)
605 		return (EINTR);
606 	return (0);
607 }
608 
609 #define	BP_SPAN(dnp, level) \
610 	(((uint64_t)dnp->dn_datablkszsec) << (SPA_MINBLOCKSHIFT + \
611 	(level) * (dnp->dn_indblkshift - SPA_BLKPTRSHIFT)))
612 
613 static int
614 backup_cb(traverse_blk_cache_t *bc, spa_t *spa, void *arg)
615 {
616 	struct backuparg *ba = arg;
617 	uint64_t object = bc->bc_bookmark.zb_object;
618 	int level = bc->bc_bookmark.zb_level;
619 	uint64_t blkid = bc->bc_bookmark.zb_blkid;
620 	blkptr_t *bp = bc->bc_blkptr.blk_birth ? &bc->bc_blkptr : NULL;
621 	dmu_object_type_t type = bp ? BP_GET_TYPE(bp) : DMU_OT_NONE;
622 	void *data = bc->bc_data;
623 	int err = 0;
624 
625 	if (issig(JUSTLOOKING) && issig(FORREAL))
626 		return (EINTR);
627 
628 	ASSERT(data || bp == NULL);
629 
630 	if (bp == NULL && object == 0) {
631 		uint64_t span = BP_SPAN(bc->bc_dnode, level);
632 		uint64_t dnobj = (blkid * span) >> DNODE_SHIFT;
633 		err = dump_freeobjects(ba, dnobj, span >> DNODE_SHIFT);
634 	} else if (bp == NULL) {
635 		uint64_t span = BP_SPAN(bc->bc_dnode, level);
636 		err = dump_free(ba, object, blkid * span, span);
637 	} else if (data && level == 0 && type == DMU_OT_DNODE) {
638 		dnode_phys_t *blk = data;
639 		int i;
640 		int blksz = BP_GET_LSIZE(bp);
641 
642 		for (i = 0; i < blksz >> DNODE_SHIFT; i++) {
643 			uint64_t dnobj =
644 			    (blkid << (DNODE_BLOCK_SHIFT - DNODE_SHIFT)) + i;
645 			err = dump_dnode(ba, dnobj, blk+i);
646 			if (err)
647 				break;
648 		}
649 	} else if (level == 0 &&
650 	    type != DMU_OT_DNODE && type != DMU_OT_OBJSET) {
651 		int blksz = BP_GET_LSIZE(bp);
652 		if (data == NULL) {
653 			uint32_t aflags = ARC_WAIT;
654 			arc_buf_t *abuf;
655 			zbookmark_t zb;
656 
657 			zb.zb_objset = ba->os->os->os_dsl_dataset->ds_object;
658 			zb.zb_object = object;
659 			zb.zb_level = level;
660 			zb.zb_blkid = blkid;
661 			(void) arc_read(NULL, spa, bp,
662 			    dmu_ot[type].ot_byteswap, arc_getbuf_func, &abuf,
663 			    ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_MUSTSUCCEED,
664 			    &aflags, &zb);
665 
666 			if (abuf) {
667 				err = dump_data(ba, type, object, blkid * blksz,
668 				    blksz, abuf->b_data);
669 				(void) arc_buf_remove_ref(abuf, &abuf);
670 			}
671 		} else {
672 			err = dump_data(ba, type, object, blkid * blksz,
673 			    blksz, data);
674 		}
675 	}
676 
677 	ASSERT(err == 0 || err == EINTR);
678 	return (err);
679 }
680 
681 int
682 dmu_sendbackup(objset_t *tosnap, objset_t *fromsnap, vnode_t *vp)
683 {
684 	dsl_dataset_t *ds = tosnap->os->os_dsl_dataset;
685 	dsl_dataset_t *fromds = fromsnap ? fromsnap->os->os_dsl_dataset : NULL;
686 	dmu_replay_record_t *drr;
687 	struct backuparg ba;
688 	int err;
689 
690 	/* tosnap must be a snapshot */
691 	if (ds->ds_phys->ds_next_snap_obj == 0)
692 		return (EINVAL);
693 
694 	/* fromsnap must be an earlier snapshot from the same fs as tosnap */
695 	if (fromds && (ds->ds_dir != fromds->ds_dir ||
696 	    fromds->ds_phys->ds_creation_txg >=
697 	    ds->ds_phys->ds_creation_txg))
698 		return (EXDEV);
699 
700 	drr = kmem_zalloc(sizeof (dmu_replay_record_t), KM_SLEEP);
701 	drr->drr_type = DRR_BEGIN;
702 	drr->drr_u.drr_begin.drr_magic = DMU_BACKUP_MAGIC;
703 	drr->drr_u.drr_begin.drr_version = DMU_BACKUP_VERSION;
704 	drr->drr_u.drr_begin.drr_creation_time =
705 	    ds->ds_phys->ds_creation_time;
706 	drr->drr_u.drr_begin.drr_type = tosnap->os->os_phys->os_type;
707 	drr->drr_u.drr_begin.drr_toguid = ds->ds_phys->ds_guid;
708 	if (fromds)
709 		drr->drr_u.drr_begin.drr_fromguid = fromds->ds_phys->ds_guid;
710 	dsl_dataset_name(ds, drr->drr_u.drr_begin.drr_toname);
711 
712 	ba.drr = drr;
713 	ba.vp = vp;
714 	ba.os = tosnap;
715 	ZIO_SET_CHECKSUM(&ba.zc, 0, 0, 0, 0);
716 
717 	if (dump_bytes(&ba, drr, sizeof (dmu_replay_record_t))) {
718 		kmem_free(drr, sizeof (dmu_replay_record_t));
719 		return (ba.err);
720 	}
721 
722 	err = traverse_dsl_dataset(ds,
723 	    fromds ? fromds->ds_phys->ds_creation_txg : 0,
724 	    ADVANCE_PRE | ADVANCE_HOLES | ADVANCE_DATA | ADVANCE_NOLOCK,
725 	    backup_cb, &ba);
726 
727 	if (err) {
728 		if (err == EINTR && ba.err)
729 			err = ba.err;
730 		return (err);
731 	}
732 
733 	bzero(drr, sizeof (dmu_replay_record_t));
734 	drr->drr_type = DRR_END;
735 	drr->drr_u.drr_end.drr_checksum = ba.zc;
736 
737 	if (dump_bytes(&ba, drr, sizeof (dmu_replay_record_t)))
738 		return (ba.err);
739 
740 	kmem_free(drr, sizeof (dmu_replay_record_t));
741 
742 	return (0);
743 }
744 
745 struct restorearg {
746 	int err;
747 	int byteswap;
748 	vnode_t *vp;
749 	char *buf;
750 	uint64_t voff;
751 	int buflen; /* number of valid bytes in buf */
752 	int bufoff; /* next offset to read */
753 	int bufsize; /* amount of memory allocated for buf */
754 	zio_cksum_t zc;
755 };
756 
757 /* ARGSUSED */
758 static int
759 replay_incremental_check(void *arg1, void *arg2, dmu_tx_t *tx)
760 {
761 	dsl_dataset_t *ds = arg1;
762 	struct drr_begin *drrb = arg2;
763 	const char *snapname;
764 	int err;
765 	uint64_t val;
766 
767 	/* must already be a snapshot of this fs */
768 	if (ds->ds_phys->ds_prev_snap_obj == 0)
769 		return (ENODEV);
770 
771 	/* most recent snapshot must match fromguid */
772 	if (ds->ds_prev->ds_phys->ds_guid != drrb->drr_fromguid)
773 		return (ENODEV);
774 	/* must not have any changes since most recent snapshot */
775 	if (ds->ds_phys->ds_bp.blk_birth >
776 	    ds->ds_prev->ds_phys->ds_creation_txg)
777 		return (ETXTBSY);
778 
779 	/* new snapshot name must not exist */
780 	snapname = strrchr(drrb->drr_toname, '@');
781 	if (snapname == NULL)
782 		return (EEXIST);
783 
784 	snapname++;
785 	err = zap_lookup(ds->ds_dir->dd_pool->dp_meta_objset,
786 	    ds->ds_phys->ds_snapnames_zapobj, snapname, 8, 1, &val);
787 	if (err == 0)
788 		return (EEXIST);
789 	if (err != ENOENT)
790 		return (err);
791 
792 	return (0);
793 }
794 
795 /* ARGSUSED */
796 static void
797 replay_incremental_sync(void *arg1, void *arg2, dmu_tx_t *tx)
798 {
799 	dsl_dataset_t *ds = arg1;
800 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
801 	ds->ds_phys->ds_flags |= DS_FLAG_INCONSISTENT;
802 }
803 
804 /* ARGSUSED */
805 static int
806 replay_full_check(void *arg1, void *arg2, dmu_tx_t *tx)
807 {
808 	dsl_dir_t *dd = arg1;
809 	struct drr_begin *drrb = arg2;
810 	objset_t *mos = dd->dd_pool->dp_meta_objset;
811 	char *cp;
812 	uint64_t val;
813 	int err;
814 
815 	cp = strchr(drrb->drr_toname, '@');
816 	*cp = '\0';
817 	err = zap_lookup(mos, dd->dd_phys->dd_child_dir_zapobj,
818 	    strrchr(drrb->drr_toname, '/') + 1,
819 	    sizeof (uint64_t), 1, &val);
820 	*cp = '@';
821 
822 	if (err != ENOENT)
823 		return (err ? err : EEXIST);
824 
825 	return (0);
826 }
827 
828 static void
829 replay_full_sync(void *arg1, void *arg2, dmu_tx_t *tx)
830 {
831 	dsl_dir_t *dd = arg1;
832 	struct drr_begin *drrb = arg2;
833 	char *cp;
834 	dsl_dataset_t *ds;
835 	uint64_t dsobj;
836 
837 	cp = strchr(drrb->drr_toname, '@');
838 	*cp = '\0';
839 	dsobj = dsl_dataset_create_sync(dd, strrchr(drrb->drr_toname, '/') + 1,
840 	    NULL, tx);
841 	*cp = '@';
842 
843 	VERIFY(0 == dsl_dataset_open_obj(dd->dd_pool, dsobj, NULL,
844 	    DS_MODE_EXCLUSIVE, FTAG, &ds));
845 
846 	(void) dmu_objset_create_impl(dsl_dataset_get_spa(ds),
847 	    ds, drrb->drr_type, tx);
848 
849 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
850 	ds->ds_phys->ds_flags |= DS_FLAG_INCONSISTENT;
851 
852 	dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, FTAG);
853 }
854 
855 static int
856 replay_end_check(void *arg1, void *arg2, dmu_tx_t *tx)
857 {
858 	objset_t *os = arg1;
859 	struct drr_begin *drrb = arg2;
860 	char *snapname;
861 
862 	/* XXX verify that drr_toname is in dd */
863 
864 	snapname = strchr(drrb->drr_toname, '@');
865 	if (snapname == NULL)
866 		return (EINVAL);
867 	snapname++;
868 
869 	return (dsl_dataset_snapshot_check(os, snapname, tx));
870 }
871 
872 static void
873 replay_end_sync(void *arg1, void *arg2, dmu_tx_t *tx)
874 {
875 	objset_t *os = arg1;
876 	struct drr_begin *drrb = arg2;
877 	char *snapname;
878 	dsl_dataset_t *ds, *hds;
879 
880 	snapname = strchr(drrb->drr_toname, '@') + 1;
881 
882 	dsl_dataset_snapshot_sync(os, snapname, tx);
883 
884 	/* set snapshot's creation time and guid */
885 	hds = os->os->os_dsl_dataset;
886 	VERIFY(0 == dsl_dataset_open_obj(hds->ds_dir->dd_pool,
887 	    hds->ds_phys->ds_prev_snap_obj, NULL,
888 	    DS_MODE_PRIMARY | DS_MODE_READONLY | DS_MODE_INCONSISTENT,
889 	    FTAG, &ds));
890 
891 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
892 	ds->ds_phys->ds_creation_time = drrb->drr_creation_time;
893 	ds->ds_phys->ds_guid = drrb->drr_toguid;
894 	ds->ds_phys->ds_flags &= ~DS_FLAG_INCONSISTENT;
895 
896 	dsl_dataset_close(ds, DS_MODE_PRIMARY, FTAG);
897 
898 	dmu_buf_will_dirty(hds->ds_dbuf, tx);
899 	hds->ds_phys->ds_flags &= ~DS_FLAG_INCONSISTENT;
900 }
901 
902 void *
903 restore_read(struct restorearg *ra, int len)
904 {
905 	void *rv;
906 
907 	/* some things will require 8-byte alignment, so everything must */
908 	ASSERT3U(len % 8, ==, 0);
909 
910 	while (ra->buflen - ra->bufoff < len) {
911 		ssize_t resid;
912 		int leftover = ra->buflen - ra->bufoff;
913 
914 		(void) memmove(ra->buf, ra->buf + ra->bufoff, leftover);
915 		ra->err = vn_rdwr(UIO_READ, ra->vp,
916 		    (caddr_t)ra->buf + leftover, ra->bufsize - leftover,
917 		    ra->voff, UIO_SYSSPACE, FAPPEND,
918 		    RLIM64_INFINITY, CRED(), &resid);
919 
920 		ra->voff += ra->bufsize - leftover - resid;
921 		ra->buflen = ra->bufsize - resid;
922 		ra->bufoff = 0;
923 		if (resid == ra->bufsize - leftover)
924 			ra->err = EINVAL;
925 		if (ra->err)
926 			return (NULL);
927 		/* Could compute checksum here? */
928 	}
929 
930 	ASSERT3U(ra->bufoff % 8, ==, 0);
931 	ASSERT3U(ra->buflen - ra->bufoff, >=, len);
932 	rv = ra->buf + ra->bufoff;
933 	ra->bufoff += len;
934 	if (ra->byteswap)
935 		fletcher_4_incremental_byteswap(rv, len, &ra->zc);
936 	else
937 		fletcher_4_incremental_native(rv, len, &ra->zc);
938 	return (rv);
939 }
940 
941 static void
942 backup_byteswap(dmu_replay_record_t *drr)
943 {
944 #define	DO64(X) (drr->drr_u.X = BSWAP_64(drr->drr_u.X))
945 #define	DO32(X) (drr->drr_u.X = BSWAP_32(drr->drr_u.X))
946 	drr->drr_type = BSWAP_32(drr->drr_type);
947 	switch (drr->drr_type) {
948 	case DRR_BEGIN:
949 		DO64(drr_begin.drr_magic);
950 		DO64(drr_begin.drr_version);
951 		DO64(drr_begin.drr_creation_time);
952 		DO32(drr_begin.drr_type);
953 		DO64(drr_begin.drr_toguid);
954 		DO64(drr_begin.drr_fromguid);
955 		break;
956 	case DRR_OBJECT:
957 		DO64(drr_object.drr_object);
958 		/* DO64(drr_object.drr_allocation_txg); */
959 		DO32(drr_object.drr_type);
960 		DO32(drr_object.drr_bonustype);
961 		DO32(drr_object.drr_blksz);
962 		DO32(drr_object.drr_bonuslen);
963 		break;
964 	case DRR_FREEOBJECTS:
965 		DO64(drr_freeobjects.drr_firstobj);
966 		DO64(drr_freeobjects.drr_numobjs);
967 		break;
968 	case DRR_WRITE:
969 		DO64(drr_write.drr_object);
970 		DO32(drr_write.drr_type);
971 		DO64(drr_write.drr_offset);
972 		DO64(drr_write.drr_length);
973 		break;
974 	case DRR_FREE:
975 		DO64(drr_free.drr_object);
976 		DO64(drr_free.drr_offset);
977 		DO64(drr_free.drr_length);
978 		break;
979 	case DRR_END:
980 		DO64(drr_end.drr_checksum.zc_word[0]);
981 		DO64(drr_end.drr_checksum.zc_word[1]);
982 		DO64(drr_end.drr_checksum.zc_word[2]);
983 		DO64(drr_end.drr_checksum.zc_word[3]);
984 		break;
985 	}
986 #undef DO64
987 #undef DO32
988 }
989 
990 static int
991 restore_object(struct restorearg *ra, objset_t *os, struct drr_object *drro)
992 {
993 	int err;
994 	dmu_tx_t *tx;
995 
996 	err = dmu_object_info(os, drro->drr_object, NULL);
997 
998 	if (err != 0 && err != ENOENT)
999 		return (EINVAL);
1000 
1001 	if (drro->drr_type == DMU_OT_NONE ||
1002 	    drro->drr_type >= DMU_OT_NUMTYPES ||
1003 	    drro->drr_bonustype >= DMU_OT_NUMTYPES ||
1004 	    drro->drr_checksum >= ZIO_CHECKSUM_FUNCTIONS ||
1005 	    drro->drr_compress >= ZIO_COMPRESS_FUNCTIONS ||
1006 	    P2PHASE(drro->drr_blksz, SPA_MINBLOCKSIZE) ||
1007 	    drro->drr_blksz < SPA_MINBLOCKSIZE ||
1008 	    drro->drr_blksz > SPA_MAXBLOCKSIZE ||
1009 	    drro->drr_bonuslen > DN_MAX_BONUSLEN) {
1010 		return (EINVAL);
1011 	}
1012 
1013 	tx = dmu_tx_create(os);
1014 
1015 	if (err == ENOENT) {
1016 		/* currently free, want to be allocated */
1017 		dmu_tx_hold_bonus(tx, DMU_NEW_OBJECT);
1018 		dmu_tx_hold_write(tx, DMU_NEW_OBJECT, 0, 1);
1019 		err = dmu_tx_assign(tx, TXG_WAIT);
1020 		if (err) {
1021 			dmu_tx_abort(tx);
1022 			return (err);
1023 		}
1024 		err = dmu_object_claim(os, drro->drr_object,
1025 		    drro->drr_type, drro->drr_blksz,
1026 		    drro->drr_bonustype, drro->drr_bonuslen, tx);
1027 	} else {
1028 		/* currently allocated, want to be allocated */
1029 		dmu_tx_hold_bonus(tx, drro->drr_object);
1030 		/*
1031 		 * We may change blocksize, so need to
1032 		 * hold_write
1033 		 */
1034 		dmu_tx_hold_write(tx, drro->drr_object, 0, 1);
1035 		err = dmu_tx_assign(tx, TXG_WAIT);
1036 		if (err) {
1037 			dmu_tx_abort(tx);
1038 			return (err);
1039 		}
1040 
1041 		err = dmu_object_reclaim(os, drro->drr_object,
1042 		    drro->drr_type, drro->drr_blksz,
1043 		    drro->drr_bonustype, drro->drr_bonuslen, tx);
1044 	}
1045 	if (err) {
1046 		dmu_tx_commit(tx);
1047 		return (EINVAL);
1048 	}
1049 
1050 	dmu_object_set_checksum(os, drro->drr_object, drro->drr_checksum, tx);
1051 	dmu_object_set_compress(os, drro->drr_object, drro->drr_compress, tx);
1052 
1053 	if (drro->drr_bonuslen) {
1054 		dmu_buf_t *db;
1055 		void *data;
1056 		VERIFY(0 == dmu_bonus_hold(os, drro->drr_object, FTAG, &db));
1057 		dmu_buf_will_dirty(db, tx);
1058 
1059 		ASSERT3U(db->db_size, ==, drro->drr_bonuslen);
1060 		data = restore_read(ra, P2ROUNDUP(db->db_size, 8));
1061 		if (data == NULL) {
1062 			dmu_tx_commit(tx);
1063 			return (ra->err);
1064 		}
1065 		bcopy(data, db->db_data, db->db_size);
1066 		if (ra->byteswap) {
1067 			dmu_ot[drro->drr_bonustype].ot_byteswap(db->db_data,
1068 			    drro->drr_bonuslen);
1069 		}
1070 		dmu_buf_rele(db, FTAG);
1071 	}
1072 	dmu_tx_commit(tx);
1073 	return (0);
1074 }
1075 
1076 /* ARGSUSED */
1077 static int
1078 restore_freeobjects(struct restorearg *ra, objset_t *os,
1079     struct drr_freeobjects *drrfo)
1080 {
1081 	uint64_t obj;
1082 
1083 	if (drrfo->drr_firstobj + drrfo->drr_numobjs < drrfo->drr_firstobj)
1084 		return (EINVAL);
1085 
1086 	for (obj = drrfo->drr_firstobj;
1087 	    obj < drrfo->drr_firstobj + drrfo->drr_numobjs; obj++) {
1088 		dmu_tx_t *tx;
1089 		int err;
1090 
1091 		if (dmu_object_info(os, obj, NULL) != 0)
1092 			continue;
1093 
1094 		tx = dmu_tx_create(os);
1095 		dmu_tx_hold_bonus(tx, obj);
1096 		err = dmu_tx_assign(tx, TXG_WAIT);
1097 		if (err) {
1098 			dmu_tx_abort(tx);
1099 			return (err);
1100 		}
1101 		err = dmu_object_free(os, obj, tx);
1102 		dmu_tx_commit(tx);
1103 		if (err && err != ENOENT)
1104 			return (EINVAL);
1105 	}
1106 	return (0);
1107 }
1108 
1109 static int
1110 restore_write(struct restorearg *ra, objset_t *os,
1111     struct drr_write *drrw)
1112 {
1113 	dmu_tx_t *tx;
1114 	void *data;
1115 	int err;
1116 
1117 	if (drrw->drr_offset + drrw->drr_length < drrw->drr_offset ||
1118 	    drrw->drr_type >= DMU_OT_NUMTYPES)
1119 		return (EINVAL);
1120 
1121 	data = restore_read(ra, drrw->drr_length);
1122 	if (data == NULL)
1123 		return (ra->err);
1124 
1125 	if (dmu_object_info(os, drrw->drr_object, NULL) != 0)
1126 		return (EINVAL);
1127 
1128 	tx = dmu_tx_create(os);
1129 
1130 	dmu_tx_hold_write(tx, drrw->drr_object,
1131 	    drrw->drr_offset, drrw->drr_length);
1132 	err = dmu_tx_assign(tx, TXG_WAIT);
1133 	if (err) {
1134 		dmu_tx_abort(tx);
1135 		return (err);
1136 	}
1137 	if (ra->byteswap)
1138 		dmu_ot[drrw->drr_type].ot_byteswap(data, drrw->drr_length);
1139 	dmu_write(os, drrw->drr_object,
1140 	    drrw->drr_offset, drrw->drr_length, data, tx);
1141 	dmu_tx_commit(tx);
1142 	return (0);
1143 }
1144 
1145 /* ARGSUSED */
1146 static int
1147 restore_free(struct restorearg *ra, objset_t *os,
1148     struct drr_free *drrf)
1149 {
1150 	dmu_tx_t *tx;
1151 	int err;
1152 
1153 	if (drrf->drr_length != -1ULL &&
1154 	    drrf->drr_offset + drrf->drr_length < drrf->drr_offset)
1155 		return (EINVAL);
1156 
1157 	if (dmu_object_info(os, drrf->drr_object, NULL) != 0)
1158 		return (EINVAL);
1159 
1160 	tx = dmu_tx_create(os);
1161 
1162 	dmu_tx_hold_free(tx, drrf->drr_object,
1163 	    drrf->drr_offset, drrf->drr_length);
1164 	err = dmu_tx_assign(tx, TXG_WAIT);
1165 	if (err) {
1166 		dmu_tx_abort(tx);
1167 		return (err);
1168 	}
1169 	err = dmu_free_range(os, drrf->drr_object,
1170 	    drrf->drr_offset, drrf->drr_length, tx);
1171 	dmu_tx_commit(tx);
1172 	return (err);
1173 }
1174 
1175 int
1176 dmu_recvbackup(char *tosnap, struct drr_begin *drrb, uint64_t *sizep,
1177     boolean_t force, vnode_t *vp, uint64_t voffset)
1178 {
1179 	struct restorearg ra;
1180 	dmu_replay_record_t *drr;
1181 	char *cp;
1182 	objset_t *os = NULL;
1183 	zio_cksum_t pzc;
1184 
1185 	bzero(&ra, sizeof (ra));
1186 	ra.vp = vp;
1187 	ra.voff = voffset;
1188 	ra.bufsize = 1<<20;
1189 	ra.buf = kmem_alloc(ra.bufsize, KM_SLEEP);
1190 
1191 	if (drrb->drr_magic == DMU_BACKUP_MAGIC) {
1192 		ra.byteswap = FALSE;
1193 	} else if (drrb->drr_magic == BSWAP_64(DMU_BACKUP_MAGIC)) {
1194 		ra.byteswap = TRUE;
1195 	} else {
1196 		ra.err = EINVAL;
1197 		goto out;
1198 	}
1199 
1200 	/*
1201 	 * NB: this assumes that struct drr_begin will be the largest in
1202 	 * dmu_replay_record_t's drr_u, and thus we don't need to pad it
1203 	 * with zeros to make it the same length as we wrote out.
1204 	 */
1205 	((dmu_replay_record_t *)ra.buf)->drr_type = DRR_BEGIN;
1206 	((dmu_replay_record_t *)ra.buf)->drr_pad = 0;
1207 	((dmu_replay_record_t *)ra.buf)->drr_u.drr_begin = *drrb;
1208 	if (ra.byteswap) {
1209 		fletcher_4_incremental_byteswap(ra.buf,
1210 		    sizeof (dmu_replay_record_t), &ra.zc);
1211 	} else {
1212 		fletcher_4_incremental_native(ra.buf,
1213 		    sizeof (dmu_replay_record_t), &ra.zc);
1214 	}
1215 	(void) strcpy(drrb->drr_toname, tosnap); /* for the sync funcs */
1216 
1217 	if (ra.byteswap) {
1218 		drrb->drr_magic = BSWAP_64(drrb->drr_magic);
1219 		drrb->drr_version = BSWAP_64(drrb->drr_version);
1220 		drrb->drr_creation_time = BSWAP_64(drrb->drr_creation_time);
1221 		drrb->drr_type = BSWAP_32(drrb->drr_type);
1222 		drrb->drr_toguid = BSWAP_64(drrb->drr_toguid);
1223 		drrb->drr_fromguid = BSWAP_64(drrb->drr_fromguid);
1224 	}
1225 
1226 	ASSERT3U(drrb->drr_magic, ==, DMU_BACKUP_MAGIC);
1227 
1228 	if (drrb->drr_version != DMU_BACKUP_VERSION ||
1229 	    drrb->drr_type >= DMU_OST_NUMTYPES ||
1230 	    strchr(drrb->drr_toname, '@') == NULL) {
1231 		ra.err = EINVAL;
1232 		goto out;
1233 	}
1234 
1235 	/*
1236 	 * Process the begin in syncing context.
1237 	 */
1238 	if (drrb->drr_fromguid) {
1239 		/* incremental backup */
1240 		dsl_dataset_t *ds = NULL;
1241 
1242 		cp = strchr(tosnap, '@');
1243 		*cp = '\0';
1244 		ra.err = dsl_dataset_open(tosnap, DS_MODE_EXCLUSIVE, FTAG, &ds);
1245 		*cp = '@';
1246 		if (ra.err)
1247 			goto out;
1248 
1249 		/*
1250 		 * Only do the rollback if the most recent snapshot
1251 		 * matches the incremental source
1252 		 */
1253 		if (force) {
1254 			if (ds->ds_prev->ds_phys->ds_guid !=
1255 			    drrb->drr_fromguid) {
1256 				dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, FTAG);
1257 				return (ENODEV);
1258 			}
1259 			(void) dsl_dataset_rollback(ds);
1260 		}
1261 		ra.err = dsl_sync_task_do(ds->ds_dir->dd_pool,
1262 		    replay_incremental_check, replay_incremental_sync,
1263 		    ds, drrb, 1);
1264 		dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, FTAG);
1265 	} else {
1266 		/* full backup */
1267 		dsl_dir_t *dd = NULL;
1268 		const char *tail;
1269 
1270 		/* can't restore full backup into topmost fs, for now */
1271 		if (strrchr(drrb->drr_toname, '/') == NULL) {
1272 			ra.err = EINVAL;
1273 			goto out;
1274 		}
1275 
1276 		cp = strchr(tosnap, '@');
1277 		*cp = '\0';
1278 		ra.err = dsl_dir_open(tosnap, FTAG, &dd, &tail);
1279 		*cp = '@';
1280 		if (ra.err)
1281 			goto out;
1282 		if (tail == NULL) {
1283 			ra.err = EEXIST;
1284 			goto out;
1285 		}
1286 
1287 		ra.err = dsl_sync_task_do(dd->dd_pool, replay_full_check,
1288 		    replay_full_sync, dd, drrb, 5);
1289 		dsl_dir_close(dd, FTAG);
1290 	}
1291 	if (ra.err)
1292 		goto out;
1293 
1294 	/*
1295 	 * Open the objset we are modifying.
1296 	 */
1297 
1298 	cp = strchr(tosnap, '@');
1299 	*cp = '\0';
1300 	ra.err = dmu_objset_open(tosnap, DMU_OST_ANY,
1301 	    DS_MODE_PRIMARY | DS_MODE_INCONSISTENT, &os);
1302 	*cp = '@';
1303 	ASSERT3U(ra.err, ==, 0);
1304 
1305 	/*
1306 	 * Read records and process them.
1307 	 */
1308 	pzc = ra.zc;
1309 	while (ra.err == 0 &&
1310 	    NULL != (drr = restore_read(&ra, sizeof (*drr)))) {
1311 		if (issig(JUSTLOOKING) && issig(FORREAL)) {
1312 			ra.err = EINTR;
1313 			goto out;
1314 		}
1315 
1316 		if (ra.byteswap)
1317 			backup_byteswap(drr);
1318 
1319 		switch (drr->drr_type) {
1320 		case DRR_OBJECT:
1321 		{
1322 			/*
1323 			 * We need to make a copy of the record header,
1324 			 * because restore_{object,write} may need to
1325 			 * restore_read(), which will invalidate drr.
1326 			 */
1327 			struct drr_object drro = drr->drr_u.drr_object;
1328 			ra.err = restore_object(&ra, os, &drro);
1329 			break;
1330 		}
1331 		case DRR_FREEOBJECTS:
1332 		{
1333 			struct drr_freeobjects drrfo =
1334 			    drr->drr_u.drr_freeobjects;
1335 			ra.err = restore_freeobjects(&ra, os, &drrfo);
1336 			break;
1337 		}
1338 		case DRR_WRITE:
1339 		{
1340 			struct drr_write drrw = drr->drr_u.drr_write;
1341 			ra.err = restore_write(&ra, os, &drrw);
1342 			break;
1343 		}
1344 		case DRR_FREE:
1345 		{
1346 			struct drr_free drrf = drr->drr_u.drr_free;
1347 			ra.err = restore_free(&ra, os, &drrf);
1348 			break;
1349 		}
1350 		case DRR_END:
1351 		{
1352 			struct drr_end drre = drr->drr_u.drr_end;
1353 			/*
1354 			 * We compare against the *previous* checksum
1355 			 * value, because the stored checksum is of
1356 			 * everything before the DRR_END record.
1357 			 */
1358 			if (drre.drr_checksum.zc_word[0] != 0 &&
1359 			    ((drre.drr_checksum.zc_word[0] - pzc.zc_word[0]) |
1360 			    (drre.drr_checksum.zc_word[1] - pzc.zc_word[1]) |
1361 			    (drre.drr_checksum.zc_word[2] - pzc.zc_word[2]) |
1362 			    (drre.drr_checksum.zc_word[3] - pzc.zc_word[3]))) {
1363 				ra.err = ECKSUM;
1364 				goto out;
1365 			}
1366 
1367 			ra.err = dsl_sync_task_do(dmu_objset_ds(os)->
1368 			    ds_dir->dd_pool, replay_end_check, replay_end_sync,
1369 			    os, drrb, 3);
1370 			goto out;
1371 		}
1372 		default:
1373 			ra.err = EINVAL;
1374 			goto out;
1375 		}
1376 		pzc = ra.zc;
1377 	}
1378 
1379 out:
1380 	if (os)
1381 		dmu_objset_close(os);
1382 
1383 	/*
1384 	 * Make sure we don't rollback/destroy unless we actually
1385 	 * processed the begin properly.  'os' will only be set if this
1386 	 * is the case.
1387 	 */
1388 	if (ra.err && os && tosnap && strchr(tosnap, '@')) {
1389 		/*
1390 		 * rollback or destroy what we created, so we don't
1391 		 * leave it in the restoring state.
1392 		 */
1393 		dsl_dataset_t *ds;
1394 		int err;
1395 
1396 		cp = strchr(tosnap, '@');
1397 		*cp = '\0';
1398 		err = dsl_dataset_open(tosnap,
1399 		    DS_MODE_EXCLUSIVE | DS_MODE_INCONSISTENT,
1400 		    FTAG, &ds);
1401 		if (err == 0) {
1402 			txg_wait_synced(ds->ds_dir->dd_pool, 0);
1403 			if (drrb->drr_fromguid) {
1404 				/* incremental: rollback to most recent snap */
1405 				(void) dsl_dataset_rollback(ds);
1406 				dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, FTAG);
1407 			} else {
1408 				/* full: destroy whole fs */
1409 				dsl_dataset_close(ds, DS_MODE_EXCLUSIVE, FTAG);
1410 				(void) dsl_dataset_destroy(tosnap);
1411 			}
1412 		}
1413 		*cp = '@';
1414 	}
1415 
1416 	kmem_free(ra.buf, ra.bufsize);
1417 	if (sizep)
1418 		*sizep = ra.voff;
1419 	return (ra.err);
1420 }
1421 
1422 typedef struct {
1423 	uint64_t	txg;
1424 	dmu_buf_impl_t	*db;
1425 	dmu_sync_cb_t	*done;
1426 	void		*arg;
1427 } dmu_sync_cbin_t;
1428 
1429 typedef union {
1430 	dmu_sync_cbin_t	data;
1431 	blkptr_t	blk;
1432 } dmu_sync_cbarg_t;
1433 
1434 /* ARGSUSED */
1435 static void
1436 dmu_sync_done(zio_t *zio, arc_buf_t *buf, void *varg)
1437 {
1438 	dmu_sync_cbin_t *in = (dmu_sync_cbin_t *)varg;
1439 	dmu_buf_impl_t *db = in->db;
1440 	uint64_t txg = in->txg;
1441 	dmu_sync_cb_t *done = in->done;
1442 	void *arg = in->arg;
1443 	blkptr_t *blk = (blkptr_t *)varg;
1444 
1445 	if (!BP_IS_HOLE(zio->io_bp)) {
1446 		zio->io_bp->blk_fill = 1;
1447 		BP_SET_TYPE(zio->io_bp, db->db_dnode->dn_type);
1448 		BP_SET_LEVEL(zio->io_bp, 0);
1449 	}
1450 
1451 	*blk = *zio->io_bp; /* structure assignment */
1452 
1453 	mutex_enter(&db->db_mtx);
1454 	ASSERT(db->db_d.db_overridden_by[txg&TXG_MASK] == IN_DMU_SYNC);
1455 	db->db_d.db_overridden_by[txg&TXG_MASK] = blk;
1456 	cv_broadcast(&db->db_changed);
1457 	mutex_exit(&db->db_mtx);
1458 
1459 	if (done)
1460 		done(&(db->db), arg);
1461 }
1462 
1463 /*
1464  * Intent log support: sync the block associated with db to disk.
1465  * N.B. and XXX: the caller is responsible for making sure that the
1466  * data isn't changing while dmu_sync() is writing it.
1467  *
1468  * Return values:
1469  *
1470  *	EEXIST: this txg has already been synced, so there's nothing to to.
1471  *		The caller should not log the write.
1472  *
1473  *	ENOENT: the block was dbuf_free_range()'d, so there's nothing to do.
1474  *		The caller should not log the write.
1475  *
1476  *	EALREADY: this block is already in the process of being synced.
1477  *		The caller should track its progress (somehow).
1478  *
1479  *	EINPROGRESS: the IO has been initiated.
1480  *		The caller should log this blkptr in the callback.
1481  *
1482  *	0: completed.  Sets *bp to the blkptr just written.
1483  *		The caller should log this blkptr immediately.
1484  */
1485 int
1486 dmu_sync(zio_t *pio, dmu_buf_t *db_fake,
1487     blkptr_t *bp, uint64_t txg, dmu_sync_cb_t *done, void *arg)
1488 {
1489 	dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1490 	objset_impl_t *os = db->db_objset;
1491 	dsl_pool_t *dp = os->os_dsl_dataset->ds_dir->dd_pool;
1492 	tx_state_t *tx = &dp->dp_tx;
1493 	dmu_sync_cbin_t *in;
1494 	blkptr_t *blk;
1495 	zbookmark_t zb;
1496 	uint32_t arc_flag;
1497 	int err;
1498 
1499 	ASSERT(BP_IS_HOLE(bp));
1500 	ASSERT(txg != 0);
1501 
1502 
1503 	dprintf("dmu_sync txg=%llu, s,o,q %llu %llu %llu\n",
1504 	    txg, tx->tx_synced_txg, tx->tx_open_txg, tx->tx_quiesced_txg);
1505 
1506 	/*
1507 	 * XXX - would be nice if we could do this without suspending...
1508 	 */
1509 	txg_suspend(dp);
1510 
1511 	/*
1512 	 * If this txg already synced, there's nothing to do.
1513 	 */
1514 	if (txg <= tx->tx_synced_txg) {
1515 		txg_resume(dp);
1516 		/*
1517 		 * If we're running ziltest, we need the blkptr regardless.
1518 		 */
1519 		if (txg > spa_freeze_txg(dp->dp_spa)) {
1520 			/* if db_blkptr == NULL, this was an empty write */
1521 			if (db->db_blkptr)
1522 				*bp = *db->db_blkptr; /* structure assignment */
1523 			return (0);
1524 		}
1525 		return (EEXIST);
1526 	}
1527 
1528 	mutex_enter(&db->db_mtx);
1529 
1530 	blk = db->db_d.db_overridden_by[txg&TXG_MASK];
1531 	if (blk == IN_DMU_SYNC) {
1532 		/*
1533 		 * We have already issued a sync write for this buffer.
1534 		 */
1535 		mutex_exit(&db->db_mtx);
1536 		txg_resume(dp);
1537 		return (EALREADY);
1538 	} else if (blk != NULL) {
1539 		/*
1540 		 * This buffer had already been synced.  It could not
1541 		 * have been dirtied since, or we would have cleared blk.
1542 		 */
1543 		*bp = *blk; /* structure assignment */
1544 		mutex_exit(&db->db_mtx);
1545 		txg_resume(dp);
1546 		return (0);
1547 	}
1548 
1549 	if (txg == tx->tx_syncing_txg) {
1550 		while (db->db_data_pending) {
1551 			/*
1552 			 * IO is in-progress.  Wait for it to finish.
1553 			 * XXX - would be nice to be able to somehow "attach"
1554 			 * this zio to the parent zio passed in.
1555 			 */
1556 			cv_wait(&db->db_changed, &db->db_mtx);
1557 			if (!db->db_data_pending &&
1558 			    db->db_blkptr && BP_IS_HOLE(db->db_blkptr)) {
1559 				/*
1560 				 * IO was compressed away
1561 				 */
1562 				*bp = *db->db_blkptr; /* structure assignment */
1563 				mutex_exit(&db->db_mtx);
1564 				txg_resume(dp);
1565 				return (0);
1566 			}
1567 			ASSERT(db->db_data_pending ||
1568 			    (db->db_blkptr && db->db_blkptr->blk_birth == txg));
1569 		}
1570 
1571 		if (db->db_blkptr && db->db_blkptr->blk_birth == txg) {
1572 			/*
1573 			 * IO is already completed.
1574 			 */
1575 			*bp = *db->db_blkptr; /* structure assignment */
1576 			mutex_exit(&db->db_mtx);
1577 			txg_resume(dp);
1578 			return (0);
1579 		}
1580 	}
1581 
1582 	if (db->db_d.db_data_old[txg&TXG_MASK] == NULL) {
1583 		/*
1584 		 * This dbuf isn't dirty, must have been free_range'd.
1585 		 * There's no need to log writes to freed blocks, so we're done.
1586 		 */
1587 		mutex_exit(&db->db_mtx);
1588 		txg_resume(dp);
1589 		return (ENOENT);
1590 	}
1591 
1592 	ASSERT(db->db_d.db_overridden_by[txg&TXG_MASK] == NULL);
1593 	db->db_d.db_overridden_by[txg&TXG_MASK] = IN_DMU_SYNC;
1594 	/*
1595 	 * XXX - a little ugly to stash the blkptr in the callback
1596 	 * buffer.  We always need to make sure the following is true:
1597 	 * ASSERT(sizeof(blkptr_t) >= sizeof(dmu_sync_cbin_t));
1598 	 */
1599 	in = kmem_alloc(sizeof (blkptr_t), KM_SLEEP);
1600 	in->db = db;
1601 	in->txg = txg;
1602 	in->done = done;
1603 	in->arg = arg;
1604 	mutex_exit(&db->db_mtx);
1605 	txg_resume(dp);
1606 
1607 	arc_flag = pio == NULL ? ARC_WAIT : ARC_NOWAIT;
1608 	zb.zb_objset = os->os_dsl_dataset->ds_object;
1609 	zb.zb_object = db->db.db_object;
1610 	zb.zb_level = db->db_level;
1611 	zb.zb_blkid = db->db_blkid;
1612 	err = arc_write(pio, os->os_spa,
1613 	    zio_checksum_select(db->db_dnode->dn_checksum, os->os_checksum),
1614 	    zio_compress_select(db->db_dnode->dn_compress, os->os_compress),
1615 	    dmu_get_replication_level(os->os_spa, &zb, db->db_dnode->dn_type),
1616 	    txg, bp, db->db_d.db_data_old[txg&TXG_MASK], dmu_sync_done, in,
1617 	    ZIO_PRIORITY_SYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, arc_flag, &zb);
1618 	ASSERT(err == 0);
1619 
1620 	return (arc_flag == ARC_NOWAIT ? EINPROGRESS : 0);
1621 }
1622 
1623 uint64_t
1624 dmu_object_max_nonzero_offset(objset_t *os, uint64_t object)
1625 {
1626 	dnode_t *dn;
1627 
1628 	/* XXX assumes dnode_hold will not get an i/o error */
1629 	(void) dnode_hold(os->os, object, FTAG, &dn);
1630 	uint64_t rv = dnode_max_nonzero_offset(dn);
1631 	dnode_rele(dn, FTAG);
1632 	return (rv);
1633 }
1634 
1635 int
1636 dmu_object_set_blocksize(objset_t *os, uint64_t object, uint64_t size, int ibs,
1637 	dmu_tx_t *tx)
1638 {
1639 	dnode_t *dn;
1640 	int err;
1641 
1642 	err = dnode_hold(os->os, object, FTAG, &dn);
1643 	if (err)
1644 		return (err);
1645 	err = dnode_set_blksz(dn, size, ibs, tx);
1646 	dnode_rele(dn, FTAG);
1647 	return (err);
1648 }
1649 
1650 void
1651 dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
1652 	dmu_tx_t *tx)
1653 {
1654 	dnode_t *dn;
1655 
1656 	/* XXX assumes dnode_hold will not get an i/o error */
1657 	(void) dnode_hold(os->os, object, FTAG, &dn);
1658 	ASSERT(checksum < ZIO_CHECKSUM_FUNCTIONS);
1659 	dn->dn_checksum = checksum;
1660 	dnode_setdirty(dn, tx);
1661 	dnode_rele(dn, FTAG);
1662 }
1663 
1664 void
1665 dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
1666 	dmu_tx_t *tx)
1667 {
1668 	dnode_t *dn;
1669 
1670 	/* XXX assumes dnode_hold will not get an i/o error */
1671 	(void) dnode_hold(os->os, object, FTAG, &dn);
1672 	ASSERT(compress < ZIO_COMPRESS_FUNCTIONS);
1673 	dn->dn_compress = compress;
1674 	dnode_setdirty(dn, tx);
1675 	dnode_rele(dn, FTAG);
1676 }
1677 
1678 /*
1679  * XXX - eventually, this should take into account per-dataset (or
1680  *       even per-object?) user requests for higher levels of replication.
1681  */
1682 int
1683 dmu_get_replication_level(spa_t *spa, zbookmark_t *zb, dmu_object_type_t ot)
1684 {
1685 	int ncopies = 1;
1686 
1687 	if (dmu_ot[ot].ot_metadata)
1688 		ncopies++;
1689 	if (zb->zb_level != 0)
1690 		ncopies++;
1691 	if (zb->zb_objset == 0 && zb->zb_object == 0)
1692 		ncopies++;
1693 	return (MIN(ncopies, spa_max_replication(spa)));
1694 }
1695 
1696 int
1697 dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole, uint64_t *off)
1698 {
1699 	dnode_t *dn;
1700 	int i, err;
1701 
1702 	err = dnode_hold(os->os, object, FTAG, &dn);
1703 	if (err)
1704 		return (err);
1705 	/*
1706 	 * Sync any current changes before
1707 	 * we go trundling through the block pointers.
1708 	 */
1709 	for (i = 0; i < TXG_SIZE; i++) {
1710 		if (list_link_active(&dn->dn_dirty_link[i]))
1711 			break;
1712 	}
1713 	if (i != TXG_SIZE) {
1714 		dnode_rele(dn, FTAG);
1715 		txg_wait_synced(dmu_objset_pool(os), 0);
1716 		err = dnode_hold(os->os, object, FTAG, &dn);
1717 		if (err)
1718 			return (err);
1719 	}
1720 
1721 	err = dnode_next_offset(dn, hole, off, 1, 1);
1722 	dnode_rele(dn, FTAG);
1723 
1724 	return (err);
1725 }
1726 
1727 void
1728 dmu_object_info_from_dnode(dnode_t *dn, dmu_object_info_t *doi)
1729 {
1730 	rw_enter(&dn->dn_struct_rwlock, RW_READER);
1731 	mutex_enter(&dn->dn_mtx);
1732 
1733 	doi->doi_data_block_size = dn->dn_datablksz;
1734 	doi->doi_metadata_block_size = dn->dn_indblkshift ?
1735 	    1ULL << dn->dn_indblkshift : 0;
1736 	doi->doi_indirection = dn->dn_nlevels;
1737 	doi->doi_checksum = dn->dn_checksum;
1738 	doi->doi_compress = dn->dn_compress;
1739 	doi->doi_physical_blks = (DN_USED_BYTES(dn->dn_phys) +
1740 	    SPA_MINBLOCKSIZE/2) >> SPA_MINBLOCKSHIFT;
1741 	doi->doi_max_block_offset = dn->dn_phys->dn_maxblkid;
1742 	doi->doi_type = dn->dn_type;
1743 	doi->doi_bonus_size = dn->dn_bonuslen;
1744 	doi->doi_bonus_type = dn->dn_bonustype;
1745 
1746 	mutex_exit(&dn->dn_mtx);
1747 	rw_exit(&dn->dn_struct_rwlock);
1748 }
1749 
1750 /*
1751  * Get information on a DMU object.
1752  * If doi is NULL, just indicates whether the object exists.
1753  */
1754 int
1755 dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi)
1756 {
1757 	dnode_t *dn;
1758 	int err = dnode_hold(os->os, object, FTAG, &dn);
1759 
1760 	if (err)
1761 		return (err);
1762 
1763 	if (doi != NULL)
1764 		dmu_object_info_from_dnode(dn, doi);
1765 
1766 	dnode_rele(dn, FTAG);
1767 	return (0);
1768 }
1769 
1770 /*
1771  * As above, but faster; can be used when you have a held dbuf in hand.
1772  */
1773 void
1774 dmu_object_info_from_db(dmu_buf_t *db, dmu_object_info_t *doi)
1775 {
1776 	dmu_object_info_from_dnode(((dmu_buf_impl_t *)db)->db_dnode, doi);
1777 }
1778 
1779 /*
1780  * Faster still when you only care about the size.
1781  * This is specifically optimized for zfs_getattr().
1782  */
1783 void
1784 dmu_object_size_from_db(dmu_buf_t *db, uint32_t *blksize, u_longlong_t *nblk512)
1785 {
1786 	dnode_t *dn = ((dmu_buf_impl_t *)db)->db_dnode;
1787 
1788 	*blksize = dn->dn_datablksz;
1789 	/* add 1 for dnode space */
1790 	*nblk512 = ((DN_USED_BYTES(dn->dn_phys) + SPA_MINBLOCKSIZE/2) >>
1791 	    SPA_MINBLOCKSHIFT) + 1;
1792 }
1793 
1794 /*
1795  * Given a bookmark, return the name of the dataset, object, and range in
1796  * human-readable format.
1797  */
1798 int
1799 spa_bookmark_name(spa_t *spa, zbookmark_t *zb, char *dsname, size_t dslen,
1800     char *objname, size_t objlen, char *range, size_t rangelen)
1801 {
1802 	dsl_pool_t *dp;
1803 	dsl_dataset_t *ds = NULL;
1804 	objset_t *os = NULL;
1805 	dnode_t *dn = NULL;
1806 	int err, shift;
1807 
1808 	if (dslen < MAXNAMELEN || objlen < 32 || rangelen < 64)
1809 		return (ENOSPC);
1810 
1811 	dp = spa_get_dsl(spa);
1812 	if (zb->zb_objset != 0) {
1813 		rw_enter(&dp->dp_config_rwlock, RW_READER);
1814 		err = dsl_dataset_open_obj(dp, zb->zb_objset,
1815 		    NULL, DS_MODE_NONE, FTAG, &ds);
1816 		if (err) {
1817 			rw_exit(&dp->dp_config_rwlock);
1818 			return (err);
1819 		}
1820 		dsl_dataset_name(ds, dsname);
1821 		dsl_dataset_close(ds, DS_MODE_NONE, FTAG);
1822 		rw_exit(&dp->dp_config_rwlock);
1823 
1824 		err = dmu_objset_open(dsname, DMU_OST_ANY, DS_MODE_NONE, &os);
1825 		if (err)
1826 			goto out;
1827 
1828 	} else {
1829 		dsl_dataset_name(NULL, dsname);
1830 		os = dp->dp_meta_objset;
1831 	}
1832 
1833 
1834 	if (zb->zb_object == DMU_META_DNODE_OBJECT) {
1835 		(void) strncpy(objname, "mdn", objlen);
1836 	} else {
1837 		(void) snprintf(objname, objlen, "%lld",
1838 		    (longlong_t)zb->zb_object);
1839 	}
1840 
1841 	err = dnode_hold(os->os, zb->zb_object, FTAG, &dn);
1842 	if (err)
1843 		goto out;
1844 
1845 	shift = (dn->dn_datablkshift?dn->dn_datablkshift:SPA_MAXBLOCKSHIFT) +
1846 	    zb->zb_level * (dn->dn_indblkshift - SPA_BLKPTRSHIFT);
1847 	(void) snprintf(range, rangelen, "%llu-%llu",
1848 	    (u_longlong_t)(zb->zb_blkid << shift),
1849 	    (u_longlong_t)((zb->zb_blkid+1) << shift));
1850 
1851 out:
1852 	if (dn)
1853 		dnode_rele(dn, FTAG);
1854 	if (os && os != dp->dp_meta_objset)
1855 		dmu_objset_close(os);
1856 	return (err);
1857 }
1858 
1859 void
1860 byteswap_uint64_array(void *vbuf, size_t size)
1861 {
1862 	uint64_t *buf = vbuf;
1863 	size_t count = size >> 3;
1864 	int i;
1865 
1866 	ASSERT((size & 7) == 0);
1867 
1868 	for (i = 0; i < count; i++)
1869 		buf[i] = BSWAP_64(buf[i]);
1870 }
1871 
1872 void
1873 byteswap_uint32_array(void *vbuf, size_t size)
1874 {
1875 	uint32_t *buf = vbuf;
1876 	size_t count = size >> 2;
1877 	int i;
1878 
1879 	ASSERT((size & 3) == 0);
1880 
1881 	for (i = 0; i < count; i++)
1882 		buf[i] = BSWAP_32(buf[i]);
1883 }
1884 
1885 void
1886 byteswap_uint16_array(void *vbuf, size_t size)
1887 {
1888 	uint16_t *buf = vbuf;
1889 	size_t count = size >> 1;
1890 	int i;
1891 
1892 	ASSERT((size & 1) == 0);
1893 
1894 	for (i = 0; i < count; i++)
1895 		buf[i] = BSWAP_16(buf[i]);
1896 }
1897 
1898 /* ARGSUSED */
1899 void
1900 byteswap_uint8_array(void *vbuf, size_t size)
1901 {
1902 }
1903 
1904 void
1905 dmu_init(void)
1906 {
1907 	dbuf_init();
1908 	dnode_init();
1909 	arc_init();
1910 }
1911 
1912 void
1913 dmu_fini(void)
1914 {
1915 	arc_fini();
1916 	dnode_fini();
1917 	dbuf_fini();
1918 }
1919